The present invention relates generally to indwelling catheters and electrode leads and more particularly to introducer systems for introducing catheters and electrode leads into a desired portion of a patient""s body.
Catheters and leads are typically placed in a desired location in a patient""s body, particularly within the patient""s vasculature, by means of introducer systems. These introducer systems typically include an elongated sheath which is inserted into the blood vessel or other portion of the patient""s body, through which sheath the catheter or lead is introduced. In those circumstances in which the lead or catheter is to remain in the patient""s body for a considerable period of time, it is desirable to be able to remove the introducer sheath over connectors or fittings on the leads or catheters, which may have diameters greater than the inner diameter of the introducer sheath.
In many circumstances, it is also desirable that a hemostasis valve be provided at the proximal end of the introducer sheath, allowing the introducer to be sealed around the lead or catheter body. The presence of the hemostasis valve, which typically includes a rigid housing containing a compressible seal which engages the circumference of the lead body, can pose a problem with regard to removal of the introducer sheath. One mechanism for including a hemostasis valve in a removable sheath is described in co-pending, commonly assigned U.S. patent application Ser. No. 09/116,628, filed Jul. 16, 1998 by Gardeski et al., incorporated herein by reference in its entirety. In the introducer disclosed in the Gardeski et al. application, the introducer sheath is provided with a luer hub on its proximal end, allowing interconnection both to the removable hemostasis valve and to other devices such as valves, T-fittings and the like, using the luer hub. The luer hub is specifically adapted to be slit using a conventional catheter slitter, which may also be employed to slit the introducer sheath.
In order to facilitate location of a catheter or lead in a specific location, it is common to provide a bend or bends in the introducer. The bend may be pre-formed as in U.S. Pat. No. 5,902,289, issued to Swartz. Alternatively, the introducer may be provided with a deflection mechanism allowing it to assume a desired bend or bends while within the vascular system of the patient, as in U.S. Pat. No. 5,484,407, issued to Osypka. Typically, introducers provided with deflection mechanisms are not adapted for removal over connectors or fittings having diameters greater than the inner diameter of the introducer sheath.
The present invention is directed to providing an introducer or guide catheter which may be employed to direct a lead or catheter to the desired location within the patient""s body. In a preferred embodiment, the invention is directed to providing an introducer or catheter having a controllable adjustable curvature in order to facilitate placement of the lead or catheter at specific desired locations in the patient""s body, which is adapted to be employed in conjunction with the implant of a permanently indwelling catheter or lead having a connector or fitting at its proximal end which has a diameter greater than the internal diameter of the lumen of the introducer sheath through which the catheter or lead is introduced. In the context of a preferred embodiment of the present invention, these objectives are accomplished by providing an introducer sheath which comprises a two lumen tube, one lumen configured to receive the lead or catheter to be introduced, the second lumen configured to receive an insertable elongated guiding member such as a stylet, which is either shapable or deflectable and which depending upon its configuration, correspondingly alters the configuration of the introducer. In order that the introducer may be reconfigured while in the patient""s body, the second lumen is provided with an internal coil or other tubular reinforcement member, allowing for insertion and removal of pre-curved stylet or other elongated guiding member while the introducer is in the patient""s body without the risk of perforation of the wall of the second lumen. In order to facilitate removal of the introducer over a lead or catheter having the connector or fitting at its proximal end which is greater than the internal diameter of the first lumen, the introducer is adapted to be slit or split along its length. In some embodiments of the invention, the catheter may be rendered splittable by provision of a weakened zone along its length, for example as described in U.S. Pat. No. 4,354,606, issued to Littleford and incorporated herein in its entirety. In a particularly desirable embodiment, the introducer is provided with a luer lock at its proximal end, facilitating connection of the introducer to a hemostasis valve, t-fitting, or the like. In this particular embodiment, the luer fitting is preferably configured to be slittable by means of a catheter slitter, and is provided with a defined weakened zone along which the luer fitting is adapted to be slit. The weakened zone of the luer lock is preferably aligned with an portion of the external wall of the first lumen of the introducer sheath located diametrically opposite the second lumen.